windowed and full screen mode

If have been trying to create an opengl application under windows that changes from windowed mode to fullscreen mode (when using the alt-return key combination). Does anyone know where I can find an explanation on how to do this, or maybe some sample code ?
Thanxx

I’m not 100% sure that I’m doing it the optimal way, but I have an app that supports this and it seems to be working properly.

E-mail me if you want a brief description and some sample code that I’m using.